This document discusses audiology concepts including types, severity, and configurations of hearing loss. It describes reasons a child may refer from OAE screening and how ABR thresholds correlate to audiograms. Specific types of hearing loss are defined, including conductive from outer/middle ear disorders, sensorineural from inner ear issues, and mixed hearing loss involving both. Causes, pathologies, and test results for each type are outlined. School hearing screening guidelines and what constitutes normal versus disordered audiometric results are also summarized.

1. Audiology Review Objectives: Describe ear-specific type, severity and configuration of a hearing loss. List reasons a child would refer OAE screening. Correlate ABR thresholds to audiogram.

2. Audiogram – Degrees of loss Normal Slight Mild Moderate Moderately-Severe Severe Profound

3. Audiogram – Types of loss Sensorineural: Bone conduction and air conduction thresholds abnormal and within 10 dB Conductive: Bone conduction thresholds normal, >10 dB Air-Bone Gap Mixed: Bone conduction thresholds abnormal, >10 dB Air-Bone Gap ] X ] X < O

4. Audiogram – Configuration of loss Configurations Flat Sloping* Rising* Notched Cookie-bite Reverse cookie-bite *Modifiers Gently (< 20 dB difference between octaves) Steeply (20-30 dB difference between octaves) Precipitously (> 30 dB difference between octaves)

5. Audiogram

6. Audiogram

7. Audiogram

8. Audiogram

9. Tympanogram Type A: Normal Peak near atmospheric pressure Type B: Abnormal No peak Needs medical attention Type C: Borderline normal Negative pressure Monitor. May need medical attention

10. Otoacoustic emissions Outer hair cell activity in cochlea adds energy to transduction process OAE equipment elicits activity and records presence of additional energy Absent OAEs Present OAEs

11. Cutoffs Absent when loss is greater than 40 dB HL (Norton 1993)

12. Pure tone thresholds most ideal School age children should be screened at the following times: first entry into school every year, K-3rd grade 7th grade 11th grade upon entrance into special education upon grade repetition upon entering a new school system without evidence of having passed a previous hearing screening (Sabo et al 2000) (ASHA)

13. ABR threshold Click threshold approximates (±10 dB) pure tone threshold 2 – 4 kHz Tone burst thresholds approximate pure tone threshold within 20 dB in 93% of children within 15 dB in 80% of children (Stapells et al 1995)

14. Normal hearing Bone and air conduction thresholds are normal (-10 – 15 dB HL) Tympanogram type A (or C) Otoacoustic emissions are present Normal ABR threshold

15. Conductive hearing loss Outer and/or middle ear disorder Bone conduction thresholds are normal Air conduction thresholds are elevated Usually tympanogram type B (sometimes C, rarely A in children) Otoacoustic emissions are absent ABR thresholds are elevated

16. Conductive pathologies Otitis media OM w/effusion can be asymptomatic Bacterial OM gluey purulent effusion greater CHL Chronic OM can lead to permanent hearing loss damage to middle ear/TM damage to basal hair cells via round window

17. Conductive pathologies Otitis media Cholesteatoma epithelial cyst erodes bone retracted TM may create pocket for epithelial cells to collect

18. Conductive pathologies Otitis media Cholesteatoma Occluded ear canal cerumen foreign objects

19. Conductive pathologies Otitis media Cholesteatoma Occluded ear canal Craniofacial anomalies Atresia Ossicular malformations

20. Sensorineural hearing loss Inner ear or retrocochlear disorder Bone and air conduction thresholds are elevated and similar Tympanogram type A (or C) Otoacoustic emissions are absent (greater than mild losses) ABR thresholds are elevated

21. Sensorineural hearing loss Congenital Maternal Infection Syndrome Mutation Acquired Meningitis Ototoxicity Cochlear Insult

22. Mixed hearing loss Outer and/or middle ear disorder AND Inner ear or retrocochlear disorder Bone conduction thresholds are elevated and air conduction thresholds are elevated more Tympanogram type B or C Otoacoustic emissions are absent ABR thresholds are elevated

23. Mixed hearing loss Separate etiologies EVA + OME Maternal CMV + Cholesteatoma Single underlying etiology CHARGE syndrome